Method of and apparatus for making propeller blades



June 27, 11933.

J. s u REs METHOD OF AND APPARATUS FOR MAKING PROPELLER BLADES Filed May 20, 1930 i LD.

INVENTOR J5 I? fiyuz. res. BY

ATTORNEYS.

Fatented June 27, 1933 r a so i 3..

JOHN SQUIRES, OF HAGEZRSTOWN, MARYLAND Application filed May 20,

This invention relates to a method of working metal tubes and particularly to making airplane propeller blades having particular relation to the formation of the tips thereof.

One of the main objects of this invention is to provide a two step method for producing an article from a tubular blank or tube by pressure, in which the parts more liable to undesirable deformation are formed in one part of the process, and then the rest of the part is formed in the second part of the process.

Another object is to provide suitable means to carry out such a method.

Another object is to provide means and methods whereby the tip of a propeller blade which is being made out of a tube may be protected from undesirable deformation during the formation process.

A further object is to provide, in a general pressing operation in forming a tubular member to another cross section by pressure, a preliminary step which comprises preshaping those portions that are to be most changed in cross section during the pressing operation, and then pressing the entire memher to its finished shape.

Numerous other objects and features of novelty will be specifically pointed out or will be apparent in the accompanying specification, claims and-drawing.

In the accompanying drawing which shows an illustrative embodiment of my invention, and in which like reference numerals apply to like parts throughout the several different views Fig. 1 is an elevation of a metal tube or blank from which my improved propeller blade is made.

. Fig. 2 is a cross sectional View of the same after the mandrel and mandrel retainer have been placed in position.

Fig. 3 is a fragmentary sectional view taken along the line 33 of Fig. 2 looking in the direction indicated.

Fig. 4: is a perspective view of the portion of the blade shown in Fig. 3 after the preliminary shaping process has been completed.-

Fig. 5is a 'cross sectional view taken along 1930. Serial No. 454,135.

the line 5 5 of Fig. 4, looking in the direc tion indicated.

Fig. 6 is a cross sectional view taken along the line 6-6 of Fig. 2, looking in the direc tion indicated.

Fig. 7 is a plan view of the mandrel positioning and retaining plate.

Fig. 8 is a cross sectional View taken along the line 8-8 of Fig. 7, loofing in the direction indicated.

Fig. 9 is a cross sectional view showing the tube in place between a pair of forming dies prior to the closing of the dies, the tube being shown in section as taken along the line 99 of Fig. 4, looking in the direction indi- 66 cated.

Fig. 10 is a view similar to Fig. 9 after the forming dies have been brought together.

Fig. 11 is a fragmentary partlally sectional view taken axially of the tube placed between the dies shown in Figs. 9 and 10, and

connected up with a suitable source of pressure.

In the formation of hollow metallic propeller blades I have foundit desirable to first produce a hollow cylindrical tube of the general conformation indicated in Figs. 1 and 2, and thereafter modify the cross sectional shape and contour of the tube to that desired in the finished blade by placing the tube between dies, as illustrated in Fig. 9, provided with suitable matching depressions conforming in shape and contour to that desired in the finished product, and then bring the dies together as illustrated in Fig. 10 35 while maintaining the interior of the tube under suitable pressure.

This internal pressure acting on the tube while it is being squeezed together by the dies acts to maintain the surface of the tube in contact with the surface of the die depression, and thereby insure the shape and contour of the finished article being in exact conformity with the shape and contour of the die depressions. However, in order to obtain the proper blade shape in the final form, it is necessary that the tube blank be tapered to relatively small cross section at its outer .end and because of the fact that the relative amount of bending of the metal at the end is great and because the internal presslmre available is sometimes limited because of certain circumstances, such pressure acting over the relatively small area of such ends is not always suflicient to overcome the tendency of the dies to bend in the face portions of the blade tips beyond the corresponding surface of the die depressions, with the result that in the finished product as comin from. the

in advance of the general pressing operation on the entire blade.

Referring to the drawing, I show in Fi s. 1 and 2 a tubular metallic blank 11 of t e general shape from which propeller blades are made as above described. The blank 11 is of generally tapered conformation, the

small end of which is adapted to form the tip of the finished blade and which end is closed. The opposite end, which is open, may be provided with a radially outwardly extending annular flange 13, by means of which the finished article may be secured in a suitable propeller hub structure. The eneral method of forming this tubular blan to the shape of the desired finished product is to close the open end of the blank 11 by a cap member such as 30 (see Fig. 11) clamped to the flange 13 by means of a ring 31 and bolts 32, the cap 30 being'provided with a suitable conduit such as 34 which is connected to a suitable source of fluid under pressure. The blank is then placed between a pair of dies such as 24 and 25 having matching depressions 28 and 29 therein which are formed to the shape and contour of the desired finished article, and the blank is formed accordingly when the die halves are brought together.

I prefer that the perimeter of the die depressions at any transverse section of the dies is in exact conformance to the perimeter of the blank 11 taken in a plane corresponding thereto, so that in pressing the blank to shape the blank will fit the die depressions over its entire surface, as indicated in Fig. 10, without necessitating stretching of the metal.

In order to prevent the inward bending of the side facesof the tip of the blade, as previously described, during this pressing operation, I prefer to first press the blade tip portion of the blank 11 to substantially its finished shape before this general pressing operation of bringing the entire blank to shape, and one method of accomplishing this tenants to the corresponding interior thickness of the corresponding portion of the finished blade tip. This forming member 14 is provided with a shank 15 which, when the member 14 is inserted to its fullest extent into a blank 11, projects slightly past the open end of the .blank, as indicated in Fig. 2, so as to enable it to be engaged by the retaining cap 16 which holds it in place.

The retaining cap consists of a circular body portion 17-having a downwardly projectlng upper frustro-conical surface 18 and a forwardly depressed radial groove 19 extending from the center to the edge thereof to provide supporting means for the reduced end 21 of the shank 15, and having an upwardly disposed horseshoe shaped flange 22, the circular part of which extends approxi mately 180 degrees of the arc of the circumference and the straight end portions of which extend parallel with the radial depression 19 on each side thereof. The axis of symmetry of the radial depression of the plate and the horseshoe flange are the same.

The upper terminal edge 23 of the upstanding horseshoe shaped flange is bent inwardly to provide an overhanging horseshoe flange. Any other suitable means for retaining the mandrel may, of course, be employed instead of the particular one shown.

The operation is as follows:

- The tubular blank 11 which may be heated to a suitable temperature if itis desired to work the metal while hot, or which is not heated at all if it is desired to work the metal while cold, is placed in a convenient position and the forming member 14 is inserted therein. Then the retaining cap '16 is slipped over the flange on the tube, by means of its open ended horseshoe flange and the end 21 of the shank 15 travels the length of the radial groove 19 until it is in a central position.

The end of the tube is now operated upon, as between suitable dies, to work the tip of the blank 11 into its final form as indicated in Fig. 4, the forming member 14 serving to rigidly support the side faces of the formed tip against undesirable inward bending beyond the point desired in the finished blade. The retaining cap 16 is then removed and the member 14 is'removed, the member 14 coming out relatively easily because of the longitudinal and transverse taper on its head.

The blank 11 is then capped as illustrated in Fig.11; interior is placed under suitable pressure; and it is then placed between the dies 24 and 25 as previously described, care being taken to locate the formed tip of the blank in proper relation to the corresponding surfaces of the die depressions; and the dies are then brought together. During this operation it will be apparent that inasmuch as the tip of the blade has already been brought to the desired shape of the final product the dies 24 and 25 will have substantially no eflect thereon, or at least will not afiect it to such an extent as to cause the appearance of the depressions in the side faces of the tip as previously described. The resalt is that the finished product conforms exactly to the shape and contour desired, and lacks the undesirable depressions in the side faces of the tip which would otherwise be liable to occur.

While I have shown in the drawing a particular illustrative form of my apparatus, various modifications may be made in the same and in the various features of construction without materially changing the invention therein, and formal changes may be made in the specific embodiment of the invention described without departing from the spirit or substance of the broad invention, the scope of which is commensurate with the appended claims.

I claim 1. In the. formation of a pro ller blade having a tip of rounded contour rom a tubular blank by pressing it to sha e between dies, the step of forming the tip 0? the blade substantially to finished size, shape and contour as a step precedent to said pressing operation.

c 2. In the formation of a propeller blade from a tubular blank by pressing it to shape between dies, the step of formin the tip of the blade substantially to finishe size, shape and contour while rigidly maintaining said tip against reduction in thickness beyond a predetermined amount as a step precedent to said pressing operation.

3. The method of forming a propeller blade from hollow metallic tube, comprising in forming one end of said tube to approximately its desired finished size, shape and contour while leaving the other end of the tube substantially unaltered, and then externally pressing said tube to its desired finished shape.

4. The method of forming a propeller blade from hollow metallic tube, comprising in forming one end of said tube to approximately its desired finished thickness while leaving the other end of the tube unaltered, and then externally pressing said tube to its desired finished shape while maintaining it under internal pressure.

5. The method of forming a propeller blade from a hollow metal tube, comprising in externally pressing the tip of said tube to its desired finished shape while rigidly supporting said tip against collapse beyond a predetermined limit, and then completing the formation of said blade by pressing it externally to the desired finished shape.

6. The method of forming a propeller blade from a hollow metal tube closed at one end. comprising in externally pressing said closed end of said tube to its desired finished shape while rigidly supporting said tip against collapse beyond a predetermined limit, and then completing the formation of said blade by pfi'essing it externally to the desired finished s ape.

7. The method of forming a propeller blade from a hollow metal tube closed at one end comprising in externall pressing said close end of said tube to its esired finished shape while rigidly supporting, said tip against collapse beyond a predetermined limit, and then completing the formation of said blade by pressing it externally to the desired finished shape, while maintaining it under internal pressure with an elastic medium.

8. In modifying the cross sectional shape of a tubular blank to an airfoil section, the successive steps of first forming the tip of said blank to shape by rigidly supporting it interiorly from collapsing beyond a predetermined point while subjecting it to external pressure, and then externally pressing the remainder of said blank to shape while maintaining the interior thereof under suitable expanding pressure.

9. The method of forming a tubular metal blank into a propeller bla e com rising in externally pressing said blank to t e desired shape by external pressure while rigidly supporting said blank interiorly over a portion of its length and internally supporting the remainder thereof under pressure with an elastic medium.

10. The method of forming an article out of a metal tube which comprises pressing those portions of the tube that are to be most changed in cross sectional configuration against a mandrel, withdrawing the mandrel, and pressing the entire tube to final form.

11. The method of forming an article out of a hollow tube comprising pre-forming the more diflicult parts of the article over a mandrel, removing the mandrel and then die pressing the entire tube.

12. The method of making a propeller blade from a tubular blank consisting in initially pressing the. parts thereof to be most changed in cross section while maintaining a positive limit to such pressing effeet on the tube, and then pressing the entire tube to final form.

13. The method of making a propeller blade that consists in forming a seamless tube, pre-forming to final airfoil configuration such portions of the tube that are to be most chan ed in cross section and then pressing the tu e to final shape.

said blan 15. An apparatus'for manufacturing pro peller blades from ta ma tubular blanks comprising a mandre having a relatively small tip portion sha d substantially to the interior shape of the nished propeller blade and having a relatively small supporting stem and means for holding the thick portion and .the stem in desired axial relation with respect to a tubular blank.

neraeae.

'16. An'appa-ratus for manufacturing pro peller blades from tapered tubular blanks comprising a mandrel having a relatively small tip portion sha ed substantially to the interior shape of the ished propeller blade and having a relatively small supporting stem and means for holding the-thick portion and the stem in desired axial relation with respect to a tubular blank, said means including a clamp having flanged portions engaging a corresponding flange upon the large end of the propeller blade blank and socket means receiving the butt end of the stem.

JOHN SQUIRES. 

